[issue10675] unittest should have an assertChanges context manager

[Raymond Hettinger]

Raymond Hettinger <rhettinger at users.sourceforge.net> added the comment:

I concur with David Murray.  Usually you care about the specific value changed to, not whether it changed at all.  The changed-by variant is even more specialized and you're better of using assertEqual since you know what the new value is supposed to be:

  assertEqual(thing.attr, x)
     ...
  assertEqual(thing.attr, x+by)

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nosy: +rhettinger

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue10675>
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